single carb fitting

Just had a top end rebuild with new valves, guides,springs and piston rings. Good compression on both cylinders but when adjusting the amals air screw, I find the left needs only 1/2 a turn out while the right is 1 turn out.
My question is if I change to a single carb conversion, how can I get this idle jet setting correct for both cylinders as one will be lean or rich.
Thanks
chris r

Not really enough info provided .... you must sort out why the idle is so mismatched .... go from there .... once you have that sorted no problem to run single mik.... your carbs could be faulty ,or ignition is ... or could be fuel supply .... if all is good with engine then look at these ..... can't really go with single carb till you identify your trouble with idle
Craig

Your wording is confusing . Going to a single card eliminates all the adjustments 2 Amals require. But it says Made in Japan on it . Ha.

Made in Japan is not a bad inscription on bikes these days .... unless you into pure restoration .... have been running both single and dual Mikuni carbs for years with less issues than my previous experiences with Amals .... just my own experience though ... I do know Amals can be good working carbs too .... just like the set and forget Mikuni option...
Craig

I`m running amal premiers 3 months old. Have even swopped jets from both carbs but still need the different settings for decent idle. No air leaks.
Boyer ignition and the battery is fully charged.
How do I check the boyer or coils as the spark doesn't look very strong, its more of a weak yellow than a blue. I have resistor caps fitted.
thanks
chris r

blacklav said:

How do I check the boyer or coils as the spark doesn't look very strong, its more of a weak yellow than a blue.

Click to expand...

Are they both 6V coils, connected in series?
http://www.boyerbransden.com/pdf/KIT00053.pdf

http://www.tioc.org/boyertest.htm
http://www.boyerbransden.com/faultfinding.html

blacklav said:

I`m running amal premiers 3 months old. Have even swopped jets from both carbs but still need the different settings for decent idle. No air leaks.

Click to expand...

First,...... your carbs should both have all the same "settings", meaning the same, needles, needle jets, main jets, throttle body cutaway sizes, etc...

Second,.... your needles have numerous slots in them where a clip is placed to adjust their height in the throttle body. Both needles should be clipped in the same slot. Check your needle clips

Third,... If you are talking about your carbs idle air screw not being the same number of turns out from fully screwed in, that can vary slightly and be normal. If there's a huge difference than that is usually a sign of something out of sorts.

The most common things that cause erradic idle are debris in the idle circuit or an air leak. For air leaks, I get the bike running and spray carb cleaner on the manifold and carb joints to see if the bike will suck in the carb cleaning liquid and cause it to stumble. Your new carbs shouldn't have any sort of idle jet blockage.

My method for setting idle air screw position is to get a general location for each as the bike idles (high idle if it needs that to maintain running) then I gently lift and lower the throttle body to micro adjust the screw position. Because the idle air screw position interacts with the early needle jet positions, raising and lowering the throttle helps you find the screw position where the transition from idle circuit and needle jet/needle have the smoothest transition...

As with no 2 cylinders will fire exactly alike, neither will 2 identical carbs draw exactly alike. One brand new carb may be a few thou sloppy whereas another may be a few thou tight.

That being said, a 1/2 turn difference on the screws is not bad at all and quite frankly is a good variance to shoot for. Anything closer is just a bonus. I think you are really splitting hairs here.

As for a single carb, you should have no problem.

It could simply be the removable pilot jet is partly but not fully blocked. I had this problem after my engine rebuild even though the carbs (also new premires) had been stored dry after draining and given a clean before refitting. The tank had been repainted and some traces of paint where found in the float bowls which may have found its way into the jet but after another good clean all has been well.

Many thanks for all the replies and apologies for the late response.
A week after fitting the new carbs it wouldn't idle at all until I cleaned out the idle jets. It ran ok for a while until I changed the plugs to Bosch ones with the three contacts ( sorry can`t remember the type ), then it started to stall. Changed the plugs back to the originals and it was a bit better ( strange ), anyway I just thought 1/2 to 3/4 turn was a bit far off the starting point of 1.5 turns.

LAB: yes there both 6v in series all the wiring is correct. I was concerned with the lack of visible spark, especially with the bosch plugs, even with the originals they are not very noticeable. yellow not blue. I`ll go over the boyer test you sent me when I get time, and will post results.

OOnortonOO: Yes both carbs are set up exactly the same, apart from the idle screw position of course.

Thanks again, will be in touch
chris r

Not sure why it should have made in Japan on it. I run a single Amal mk2. Tick over perfect evertime, only thing is doesn't pull as well as I would expect over 5000 revs or so but its only a 32mm so not really surprising.